The effect of dextran on the lysability of ex vivo thrombi.

The lysability was determined of thrombi formed in Chandler tubes before and after infusion of 500 ml dextran 70 to patients undergoing cholecystectomy. 125I-labelled fibrinogen was given the day before operation. Following incubation of the thrombi formed in plasmin, radioactivity remaining in the thrombi and released to the supernatant was determined, as well as fibrinolytic degradation products in the supernatant, using an immunoelectrophoretic method. The dextran infusion was found to increase the radioactivity released from the thrombi to the supernatant from 15.5 plus or minus 7.6% to a maximum of 27.3 plus or minus 8.2% four hours after the infusion (P less than 0.001). A corresponding significant rise of the FDP concentration in the supernatant from 16.8 mug/ml to 44.1 mug/ml was found at the same time. After 24 hours the radioactivity had returned to initial values. The results indicate that dextran infused into patients during surgery increases the lysability of thrombi. It is suggested that this finding at least partly explains the antithrombotic effect of dextran.